Process for breaking petroleum emulsions



Patented July 1, 1952 PROCESS FOR BREAKING PETROLEUM EMULSIONS Melvin De Groote, St. Louis, Mo., assign'or' to Petrolite Corporation, Ltd., Wilmington, DeL, a

corporation of Delaware No Drawing. Application September 25, 1950, Serial No. 186,681

My invention provides an economical and rapid process for resolving petroleum emulsions of the 'water-in-oil type that are commonly referred to as cut oil, roily oil, emulsified oil, etc., and which comprise fine droplets of naturally-occurring Waters or brines dispersed in a more or less permanent state throughout the oil which constitutes the continuous phase of the emulsion.

It also provides an economical and rapid process for separating emulsions which have been prepared under controlled conditions from mineral oil, such as crude oil and relatively soft waters or weak brines. Controlled emulsification and subsequent demulsification under the conditions just mentioned are of significant value in removing impurities, particularly inorganic salts, from pipeline oil.

Demulsification as contemplated in the present application includes the preventive step of commingling the demulsifier with the aqueous component which would or might subsequently become either phase of the emulsion in the absence of such precautionary measure. Similarly, such demulsifier may be mixed with the hydrocarbon component.

The demulsifying agent employed in the present process is a fractional ester salt of a tribasic acid in which two carboxyl radicals appear in ester form and a sulfo radical appears in a salt form. Such compounds are derived preferably by reaction between three types of reagents; (a) polypropylene glycol of a molecular weight sufiicient to give water-insolubilityand kerosenesolubility, generally being in the molecular weight range of 750 to approximately 3,000; (b) a dicarboxy compound selected from the class consisting of maleic acid (or anhydride), citraconic acid (or anhydride), and fumaric acid; and (c) an alkali metal bisulfite such as sodium bisulfite or potassium bisulfite.

The preparation of the demulsifying agent involves substantially two steps; (a). Esterification between two moles of the poly-propylene glycol and one mole of a dicarboxy compound such as maleic anhydride, and (b) reaction of such fractional ester with a suitable alkali metal bisulfite such as sodium bisulfite.

More specifically then the present invention is concerned with a process for breaking petroleum emulsions of the water-in-oil type characterized by subjecting the emulsion to the action of a demulsificr including hydrophile synthetic proda 7 Claims. (Cl. 252335) ucts; said hydrophile synthetic products "being characterized by the following formula: I H 0 i HO(CsHaO.)n-l-PHO-C3HthOH some 0 0 list 7 is the divalent radical of 32th unsaturated dicarboxy acid selected from the class consisting of maleic acid, fumaric acid, and citraconic acid, and n is a whole number varying from 12 to 80, and with the proviso that thepolypropylene glycol prior to esterification be Water-insoluble and kerosene-soluble. c '1 ,x

In the above formula the alkali metal cation is shown as sodium-which is the cheapest and most readily available. Needless to say, any other alkali metal cation, such as potassium, may be employed in the form of potassium bisulfite and is included in the hereto attached claims as the obvious chemical equivalent. Similarly, ammonium bisulfite may be employed instead of sodium or potassium bisulfite. This applies also to a bisulfite of various organic bases provided, of course, that such bases prior to forming a sulfite are as basic as ammonia and that the sulfi'te water-soluble. All-these are the obvious functionalequivalents of sodium bisulfite. The procedure is illustrated by the following example;

Example 1 in which due to uncombined maleic acid radicals and the the obvious reason that if water were removed and the sodium bisulfite were anhydrous there would be little or no opportunity for reaction. This was necessary also for the reason that 4 amounts can be used, for instance, /g% or based on amount of glycol, provided, however, that the esterification time is extended somewhat.

The products obtained are comparable to the initial glycol in appearance, etc., i. e., usually they are an amber color or at least of a slight straw color, 'and often somewhat thicker than the original glycol. This description, of course, applies to materials after the removal of the solvent, 1. e., the xylene. For use as demulsifiers there is no need to remove the xylene and it may remain behind. Obviously other liquids than xylene may be used in esterification prosodium bisulfite begins to decompose at about 10' f' However if boiling point is any 100 C. and this reaction obviously must be con- 0? than Xylene there danger that decom" ducted at a suitable temperature until the soposltlqn i ke place unless the amount of dium bisulfite has combined Thereafter the sulfomc acid is reduced. Other catalysts such xylene can be distilled over in the usual manner, as a Small amount of dry hydrochloric acid can removing any water with it and all the xylene be used but it appears less desirable than the can be removed by distillation, particularly vacsulfonic acid. Needless to say, the caustic soda uum distillati n, solution used neutralizes the sulfonic acid. cata- The same procedure was followed in connecy P e ttion with a number. of additional samples, all 5 The equipment used in esterification proof which are illustrated in the following table cedure is a resin pot of the kind described in which gives the reactants, amounts employed, U. s. Patent No. 2,499,370, dated March '7, 1950, temperature of esteriflcation, etc. to De Groote and Keiser. Any conventional Table 1 Max. Max.

' gag-r8! i lDi-carboxy Reactant Xylene c lfi o i i lag-stair)? Bsiggi 3 :1? 1:53:

$523? (828-) (w) 255 (133 (55;) 2 59- as 2,025 505 MaleicAnhydride s 50 145 3% 8 80-95 a 725 115 do s 40 140 5 s 80-95 5% 1,025 8 43 139 4 8 80-95 4% 2,525 8 50 145 4 a 80-95 5% 1,525 5 45 140 5% 8 80-95 4 5..... 2,025 9 50 142 3% 5 -95 4% 725 9 139 4 5 80-95 3% 8..... 1,025 9 144 3% 8 80-95 3 0---" 2,525 9 00 145 3% 8 -95 4 10--. 1,525 9 45 140 3% 8 80-95 4% Polypropylene glycols are commercially availequipment can be used, either on a-small scale, able. Such polypropylene glycols are furnished 45 pilot plant scale, or larger scale.- in various molecular weight ranges. The water- In the various examples preceding only one insoluble, kerosene-soluble polypropylene glycols glycol has been used in these cases. Actually begin in the molecular weight range somewhere there is no reason why one may not use two difabove 500, and more specifically, at about 700 ferent glycols, for instance, an equimolar mixture or 750. The molecular weight was usually deter- 50 of two glycols, one for example having a molecumined by the hydroxyl method. Such hydroxyl lar weight of 2000 and the other 3000; or one havmolecular weight is a fraction, sometimes a ing a molecular weight of 1500 and the other large major fraction, of the theoretical molec- 2500, Actually these glycols are cogeneric mixular weight based on the method of synthesis, tures at each selected molecular weight. If one i. e., the calculated molecular weight based does make a mixture of the kind here described theoretically on the value one would expect to actually three types of compounds will appear, obtain by treating water or propylene glycol, one type in which both carboxyl radicals of the .for example, with propylene oxide. Needless polycarboxy acid are joined with the higher to say, one does not obtain a single compound molecular weight glycol, one type where both but a propylene glycol of amolecular weight carboxyls are joined with the lower molecular ratio of 750 or 1,000 or 2,000 as the case may Weight glycol, and one type where one carboxyl be, and really represents a cogeneric mixture is united to a higher molecular weight glycol and whose statistical average molecular weight is the the other one to a lower molecular weight glycol. one indicated. Reference in the table is, of The products so obtained are peculiar (a) insocourse, to hydroxyl value molecular weight for 5 far that there is not present any radical having .the obvious reason that this is the basis for cal- 8 or more uniniterrupted carbon atoms, and (b) culating the amount of reactants required. the compounds are not particularly effective as In all instances a small amount of 30% caustic surface-active agents in the ordinary sense due soda solution was used as in the more comeither to the large molecular size or the absence plete description of Example 1; and also an of a hydrophobe radical of the kind previously amount of toluene sulfonic acid, approximately referred for-Some other reason which is 1% of the weight of the glycol, or slightly less, obscure. The chemical compounds herein emwas used in the esterif cation step. The larger ployed as demulsifiers have molecular weights amount should not beuse d because there may ,varying from more than 1000 upto several be decomposition of the glycol. Smaller thousands, for instance, 5000,6000 or 7000, and

yet contain only one sulfo radical. Utility of such compounds for industrial uses is rather unusual. They are not efiective emulsifying agents but are useful for other purposes. For example, they are valuable as an additive or apromoter of emulsions. These compounds also have hydrotropic property and serve as common solvents in the preparation of micellar solutions. It is to be noted that they are free from terminal 'carboxyl radicals and thus difier from reagents obtained, for example, by treating one -mole of a high molal polypropylene glycol with 2 moles of a dicarboxy acid. It is probable these reagents, due to their peculiar structure and their peculiar solubility characteristics, will find utility in other fields of application now unknown.

Conventional demulsifying agents employed in the treatment of oil field emulsions are used as such, or after dilution with any suitable solvent, such as water, petroleum hydrocarbons, such as benzene, toluene, xylene, tar acid oil, cresol, anthracene oil, etc. Alcohols, particularly aliphat'ic alcohols, such as methyl alcohol, ethyl alcohol, denatured alcohol, propyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol, etc., may be employed as diluents. Miscellaneous solvents such as pine oil, carbon tetrachloride, sulfur dioxide extract obtained in the refining of petroleum, etc., may be employed as diluents. Similarly, the material or materials employed as the demulsifying agent of my process may be admixed with one or more of the solvents customarily used in connection with conventional demulsifying agents. Moreover, said material or materials may be used alone or in admixture with other suitable well known classes or demulsifying agents.

It is well known that conventional demulsiiy ing agents may be used in a water-soluble form, or in an oil-solubl form, or in a form exhibiting both oiland water-solubility. Sometimes they may be used in a form which exhibits'relatively limited oil-solubility. However, since such reagents are frequently used in a ratio of 1 to 10,000

or 1 to 20,000, or 1 to 30,000, or even 1 to 40,000,

or 1 to 50,000 as in desalting practice, such an apparent insolubility in oil and water is not significant because said reagents undoubtedly have solubility within such concentrations. This same fact is true in regard to the material or materials employed as the demulsifying agent of my process.

- In practicing my process for resolving petroleum emulsions of the water-in-oil type, a treating agent or demulsifying agent of the kind above described is brought into contact with or caused to act upon the emulsion to be treated, in any of the various apparatus now generally used to resolve or break petroleum emulsions with a chemical reagent, the above procedure being used alone or in combination with other demulsifying procedure, such as the electrical dehydration process.

One type of procedure is to accumulate a volume of emulsified oil in a tank and conduct a batch treatment type of demulsification procedure to recover clean oil. In this procedure the emulsion is admixed with the demulsifier, for example by agitating the tank of emulsion and slowly dripping demulsifier into the emulsion. In some cases mixing is achieved by heating the emulsion while dripping in the demulsifier, depending upon the convection currents in the emulsion to produce satisfactory admixture. In a third modification of this type of treatment, a circulating pump withdraws emulsion from, e. g., the bottom of the tank, and reintroduces it into the top of the tank,

'6 the demulsifier being added, for example, at the suction side of said circulating pump.

In a second type of treating procedure, the demulsifier is introduced into the well fluids at the well-head or at som point between the wellhead and the final oil. storage tank, by means of an adjustable proportioning mechanism or proportioning pump. Ordinarily the flow of fluids through the subsequent lines and fittings suflices to produce the desired degree of mixing of demulsifier and emulsion, although in some instances additional mixing devices may be introduced into the flow system. In this general procedure, the system may include various mechanical devices for withdrawing free water, separating entrained water, or accomplishing'quiescent settling of the chemicalized emulsion. Heating devices may likewise be incorporated in any of the treating procedures described herein.

A third type of application (down-the-hole) of demulsifier to emulsion is to introduce the .de- 'mulsifier either periodically or'continuously in diluted or undiluted form into the well and to allow it to come to the surface with the well fluids, and then to flow the chemicalized emulsion through any desirable surface equipment, such as employed in the other treating procedures. This particular type of application is decidedly'use ful when'the demulsifier is usedin connection with acidification of calcareous oil-bearing strata, especially if suspended in or dissolved in the acid employed for acidification.

In all cases, it will be apparent from the foregoing description, the broad process consists simply in introducing a relatively small proportion of demulsifier into a relatively large proportion of emulsion, admixing the chemical and emulsion either through natural flow or through special apparatus, with or without the application of heat, and allowing the mixture to stand quiescent until the undesirable water content of the emulsion separates and settles from the mass.

The following is a typical installation.

A reservoir to hold the demulsifier of the kind described (diluted or undiluted) is placed at the well-head where the eflluent liquids leave the well. This reservoir or container, which may vary from 5 gallons to gallons for convenience, is connected to a proportioning pump which injects the demulsifier drop-wise into the fluids leaving the well. Such chemicalized fluids pass through the flowline into a settling tank. The settling tank consists of a tank of any con venient size, for instance, one which will hold amounts of fluid produced in 4 to 24 hours (500 barrels to 2000 barrels capacity), and in which there is a perpendicular conduit from the top of the tankto almost the very bottom so as to permit the incoming fluids to pass from the top of the settling tank to the bottom, so that such incoming fluids do not disturb stratification which takes place during the course of demulsification. The settling tank has two outlets, one being below the water level to drain oiT the water resulting from demulsification or accompanying the emulsion as free water, the other being an oil outlet at the top to permit the passage of dehydrated oil to a second tank, being a storage tank, which holds pipeline or dehydrated oil. If desired, the conduit or pipe which serves to carry the fluids from the well to the settling tank may include a section of pipe with bailles to serve as a mixer, to insure thorough distribution of the demulsifier throughout the fluids, or a heater for raising the temperature 7 of the fluids to some convenient temperature, for instance, 120 to 160 F., or both heater and mixer.

' Demulsification procedureis started by simply setting the pump so as to feed a comparatively large ratio of demulsifier, for instance, 1:5,000.

As soon as a complete break or satisfactory demulsification is obtained, the pump is regulated until experience shows that the amount of demulsifier being added is just suificient to produce clean or dehydrated oil. The amount being fed at such stage is usually 1:l0,000, 1:15,000, 120,000, or the like.

In many instances the products herein specified as demulsifiers can be conveniently used without dilution. However, as previously noted, they may be diluted as desired with any suitable solvent. For instance, by mixing 75 parts by weight of such derivative, for example, the product of Example 'l with 15 parts by weight of xylene and 10 parts by weight of isopropyl alcohol, an excellent demulsifier is obtained. Selection of the solvent will vary, depending upon the solubility characteristics of the oxyalkylated product, and of course will be dictated in part by economic considerations, i. e., cost.

As noted above. the products herein described may be used not only in diluted form, but also may be used admixed with some other chemical demulsifier.

Having thus described my invention what I claim as new and desire to secure by Letters Patent, is: Y

1. A process for breaking petroleum emulsions of the water-in-oil type characterized by subjecting the emulsion to the action of a demulsifier including hydropile synthetic products; said hydropile synthetic products being characterized by the following formula:

H 0 t t Romano)" R- (common OaNa in which is the'divalent radical of an unsaturated dicarboxy acid selected from the class consisting of maleic-acid, fumaric acid, and citraconic acid, and n is a whole number varying from 12 to 80, and with-the proviso'that the corresponding polypropylene glycol of the formula HO(C3H6O)11.H be water-insoluble and kerosene-soluble.

2. The process of claim 1 wherein the dicarboxy acid is maleic acid.

3. The process of claim 1 wherein the dicarboxy acid is maleic acid and the value of n corresponds to a polypropylene glycol of approximately 700 molecular weight.

4. The process of claim 1 wherein the dicarboxy acid is maleic acid and the value of n corresponds to a polypropylene glycol of approximately 1000 molecular weight. A

5. The process of claim 1' wherein the dicarboxy acid is maleic acid and the valueofn corresponds to a polypropylene glycol of approximately 1500 molecular weight. Y

6. The process of claim 1 wherein the dicarboxy acid is maleic acid and the value of -n'corresponds to a polypropylene glycol of approximately 2000 molecular weight. a

7. The process of claim 1 wherein the dicarboxy acid is maleic acid and the value of n corresponds to a polypropylene glycol of approximately 2500 molecular weight. 1

MELVIN DE: (moors.

, REFERENCES CITED The following references are of record in the file of this patent: I 1

UNITED STATES PATENTS 

1. A PROCESS FOR BREAKING PETROLEUM EMULSIONS OF THE WATER-IN-OIL TYPE CHARACTERIZED BY SUBJECTING THE EMULSION TO THE ACTION OF A DEMULSIFIER INCLUDING HYDROPILE SYNTHETIC PRODUCTS; SAID HYDROPILE SYNTHETIC PRODUCTS BEING CHARACTERIZED BY THE FOLLOWING FORMULA: 